linux-kernel - Re: Performance/resume issues on Toshiba NB305

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Message-ID: <alpine.LFD.2.00.1103012117010.2701@localhost6.localdomain6>
Date:	Tue, 1 Mar 2011 21:22:46 +0100 (CET)
From:	Thomas Gleixner <tglx@...utronix.de>
To:	Seth Forshee <seth.forshee@...onical.com>
cc:	Len Brown <lenb@...nel.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	"H. Peter Anvin" <hpa@...or.com>,
	Arjan van de Ven <arjan@...radead.org>,
	Venkatesh Pallipadi <venki@...gle.com>
Subject: Re: Performance/resume issues on Toshiba NB305

On Tue, 1 Mar 2011, Seth Forshee wrote:
> On Fri, Feb 25, 2011 at 10:47:16PM +0100, Thomas Gleixner wrote:
> > On Fri, 25 Feb 2011, Seth Forshee wrote:
> > > On Fri, Feb 25, 2011 at 09:37:39PM +0100, Thomas Gleixner wrote:
> > > > On Fri, 25 Feb 2011, Seth Forshee wrote:
> > > > That seems to be related to low power states. When the machine goes
> > > > idle we switch into lower power states and that requires to use the
> > > > hpet instead of the local apic timer as that one stops.
> > > > 
> > > > You could verify that theory by booting with processor.max_cstate=1
> > > 
> > > This fixes the performance in combination with intel_idle.max_cstate=0.
> > > Alternately, intel_idle.max_cstate=1 works. But the resume still hangs.
> > 
> > That was expected :)
> > 
> > > Is the answer to quirk the machine to avoid deep C-states, or is there
> > > some better way I can fix this?
> > 
> > Let's wait for the intel and acpi folks. It would be interesting what
> > the new intel toy says to your BIOS.
> 
> Since the discussion on this issue died without really getting anywhere,
> I went ahead and threw together the patch below to disable anything
> deeper than C1 for this machine. I hope a better solution can be found,
> but if not would something like this be an acceptable workaround?
> 
> As for the hangs during resume, unless someone has a better suggestion I
> guess I'll start looking into forcing the HPET to remain in periodic
> mode throughout suspend.

The problem with such DMI quirks is that it's hard to get rid of them
when a fixed BIOS version comes out while simply adding nohpet to the
kernel command line, is a non permanent, but sensible workaround.

Thanks,

	tglx


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